The present invention relates to an electroluminescent device and a method for fabricating the same and, more particularly, to an active matrix organic electroluminescent device with high color purity and fabrication method thereof.
Recently, with the development and wide application of electronic products such as mobile phones, PDA, and notebook computers, there has been increasing demand for flat display devices which consume less electric power and occupy less space. Organic electroluminescent devices are self-emitting and highly luminous, with wider viewing angle, faster response speed, and a simple fabrication process, making them an industry display of choice.
Organic light-emitting diodes (OLED) use an organic electroluminescent layer. The trend in organic electroluminescent display technology is for higher luminescent efficiency and longer lifetime. As a result, an active matrix organic electroluminescent device with thin film transistors has been developed to solve the aforementioned problems. The active matrix organic electroluminescent device has panel luminescence with thin and lightweight characteristics, spontaneous luminescence with high luminescent efficiency and low driving voltage, and advantages of increased viewing angle, high contrast, high-response speed, flexibility and full color. As the need for larger display devices with higher resolution grows, active matrix organic electroluminescent devices are poised to achieve a major market trend.
FIG. 1 is a sectional diagram of a conventional active matrix organic electroluminescent device 100, comprising a substrate 10, a TFT array 20, red light emitting diode R, green G, and blue light emitting diode B. Each of light emitting diodes R, G, and B comprises an ITO electrode serving as an anode 30, electroluminescent layers 40, and a metal electrode serving as a cathode 50. Particularly, to isolate the light emitting diodes R, G, and B from interference, a pixel definition layer 60 is formed between each two adjacent light emitting diodes. However, since transparent compounds serve as the pixel definition layer 60 in the conventional active matrix organic electroluminescent device 100, the side emitting light 42 from one light emitting diode (such as red light emitting diode R) infringes on adjacent light emitting diodes (such as blue and green light emitting diodes B and G) through reflection of the cathode 50, resulting in light leakage and luminescent interference.
To overcome the drawbacks described, opaque organic compounds have replaced transparent compounds, for the pixel definition layer. However, the opaque organic compounds, such as pigment, generally comprise carbon-containing material with conductivity or low dielectric constant, resulting in inferior electrical and optical characteristics. Further, since the side emission of light emitting diodes is absorbed by the opaque organic compounds, luminance efficiency is reduced.
Thus, in order that luminance efficiency not be reduced, an active matrix organic electroluminescent device with high color purity is called for.